This invention relates to a furnace, and more particularly to a furnace which is usable in home heating.
The particular furnace described herein is a combination furnace, in that it includes an electric heating section and a solid fuel, i.e., wood burning section. The electrically powered heating section and the fuel burning section may be installed with individual remote thermostats controlling heat output. The thermostat for the wood burning section may be set at the desired room temperature, with the thermostat for the electrically powered heating section at the minimum desired room temperature, a few degrees lower. With this type of installation, the electrically powered heating section then serves as a backup for the wood or fuel burning section. The arrangement also makes it possible to actuate both the wood burning section and the electrically powered heating section at the same time, by simply turning both thermostats to settings above room temperature.
The furnace of the invention also features a construction wherein it may be mounted in a relatively confined space. As a consequence, the furnace is well adapted for mobile home installation, where, typically, space for mounting a furnace is limited. While well suited for mobile home installation, the furnace, of course, can be utilized for fulfilling other heating requirements.
A feature of the furnace of the invention is the provision of a fire box having metallic, i.e., heat conductive walls, which forms the solid fuel combustion chamber in the furnace. Combustion products pass upwardly from this combustion chamber and thence through a metallic heat exchanger disposed above the fire box. From the heat exchanger the combustion products pass upwardly through a flue which connects with the usual chimney, exhausting to the atmosphere. Damper means is provided, including a fire draft damper which controls the admission of fresh air to the fire box, and a balance draft damper controlling the admission of fresh air to the heat exchanger disposed above the fire box. The dampers work oppositely to each other, which is to say that when one is opened the other is closed. Further explaining, when the room thermostat calls for heat, the balance draft damper controlling air flow to the heat exchanger closes and the fire draft damper controlling air flow to the combustion chamber opens, to increase the burning rate of fuel in the fire box and the heat given off by the fire box and the heat exchanger thereabove. On a given limit temperature being reached, the fire draft damper closes and the balance draft damper opens, which has the effect of reducing the burning rate of the fuel and allowing cool air to circulate through the upper heat exchanger and out the flue. This rapidly drops the temperature of the heat exchanger, and also has the effect of flushing out creosote and other residuals which might contribute to a fire hazard in the flue system.
A blower, located adjacent the top of the furnace, when actuated, pulls air inwardly through a return air port located adjacent the top of the furnace, and forces such air downwardly through the furnace, first over an electrically powered heating section, and thence over the heat exchanger and fire box above-described. With no power delivered to the electrically powered heating section, such air is heated solely by the heat exchanger and the fire box. With fuel burning in the fire box, and with electric power delivered to the electrically powered heating section, such air is heated by both instrumentalities. The electrically powered heating section, heat exchanger and fire box are all mounted within an insulated, upstanding furnace casing functioning to channel air being heated downwardly through the furnace as such passes over the electrically powered heating section, heat exchanger and combustion chamber, finally to flow into a supply plenum for heated air located adjacent the base of the furnace.
Objects of the invention, therefore, include the provision of a practical, solid fuel burning and electrically powered combination furnace for home heating applications; the provision in a furnace, with solid fuel burning capability, of a fire box forming the combustion chamber connecting with a secondary heat exchanger, and damper means including a fire draft damper and a balance draft damper effective to control burning rate and heat exchanger temperature; the provision of a furnace with an insulated casing forming the exterior of the furnace, adapting it for mounting in a confined space; and the provision of a furnace with solid fuel burning and electrically powered capability which may be manufactured as a factory built unit, and is relatively easily installed.
These and other objects and advantages are attained by the invention, which will become more fully apparent from a reading of the following description, which is to be taken in conjunction with the accompanying drawings, wherein: